Firefox - "error processing the request"

I have been getting multiple error messages on the screen when I try to see my chess games. This started on Tuesday, and I am using in Firefox Quantum 67.0.3. No problems when I use Google Chrome.

Can you try clearing your cache in firefox and see if you still have the issue?

After clearing the cache, I exited and restarted Firefox. I am still getting the screen of red error messages when I click on "home" in the sidebar menu. Now I can see my game if I click on "play" in the sidebar menu. 

I get those a lot on Firefox---not that many, but maybe one, two or three at a time. I just close them and go on.

Same with Chrome

I use chrome too but never experience that issue with it.

Happens from time to time if I'm trying to edit my forum posts. I'm using Firefox focus.